Method of fabricating a display device with step configuration in the insulating layer

ABSTRACT

A display device includes: a substrate; a plurality of light-emission elements arranged, on the substrate, in a first direction and a second direction intersecting each other, each of the light-emission elements having a first electrode layer, an organic layer including a luminous layer, and a second electrode layer which are laminated in that order; and a separation section disposed, on the substrate, between the light-emission elements adjacent to each other in the first direction, the separation section having two or more pairs of steps. The first electrode layers in the light-emission elements are separated from each other, and the organic layers as well as the second electrode layers in the light-emission elements adjacent to each other in the first direction are separated from each other by the steps included in the separation section.

RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. §120 as adivisional application of U.S. patent application Ser. No. 13/206,762,filed Aug. 10, 2011, which claims priority to Japanese PatentApplication No. 2010-182470, filed in the Japan Patent Office on Aug.17, 2010, the entire contents of each of which are incorporated hereinby reference.

BACKGROUND

The present disclosure relates to a display device having aself-luminous light-emission element including an organic layer and amethod of producing the display device.

In recent years, as a display device substituting for a liquid crystaldisplay, an organic EL (electroluminescence) display using aself-luminous organic light-emission element including an organic layerhas been made practical. The organic EL display is of self-luminous typeand thus has a wide viewing angle compared to a liquid crystal and thelike, as well as having sufficient responsiveness to a high-definitionhigh-speed image signal.

For the organic light-emission element, so far, an attempt has been madeto improve display performance by introducing a resonator structure, andcontrolling light produced in a luminous layer, like improving a colorpurity of a luminous color or increasing luminous efficiency (forexample, see International Publication No. WO01/39554). For instance, ina top-emission system in which light is extracted from a surface (topsurface) opposite to a substrate, there is adopted a structure in whichan anode electrode, an organic layer, and a cathode electrode arelaminated sequentially via a drive transistor on a substrate; andmulti-path reflection of light from the organic layer is caused betweenthe anode electrode and the cathode electrode.

In an ordinary organic EL display, for example, an organiclight-emission element that emits red light, an organic light-emissionelement that emits green light, and an organic light-emission elementthat emits blue light are arranged sequentially and repeatedly in animage display region. Those luminous colors vary depending on a materialforming an organic layer of each color. Therefore, it is desirable toform the organic layers individually for the respective luminous colors,when forming each organic light-emission element. It is to be noted thatin an ordinary organic EL display, an anode electrode and an organiclayer are divided for every organic light-emission element, whereas acathode electrode is one-piece to be shared by two or more (preferably,all) organic light-emission elements. Here, the organic layers in therespective organic light-emission elements adjacent to each other areseparated from each other by an insulating layer. This insulating layerhas an opening to define an emission region in each organiclight-emission element.

Formation of the organic layer is performed, for example, by vapordeposition. At the time, the deposition is performed using a shadow maskhaving an opening according to an emission region and thus, it isdesirable to align the opening of the insulating layer defining theemission region precisely with the opening of the shadow mask. Recentlyhowever, there has been a trend to narrow the width of the insulatinglayer and reduce the interval between the adjacent organiclight-emission elements, in order to improve the ratio of the emissionregion of all the organic light-emission elements to the entire imagedisplay region, namely, a numerical aperture. For this reason, it isexpected in future that if the above-mentioned interval is furtherreduced, it will be difficult to fill each emission region with apredetermined organic layer sufficiently with reliability. This isbecause there is such a concern that it might be difficult to ensuresufficient accuracy of alignment between the opening of the insulatinglayer and the opening of the shadow mask, or sufficiently ensureprocessing accuracy of the shadow mask itself, or the like. When theopening of the insulating layer is not filled with the organic layersufficiently with reliability due to such a production error, desiredluminance at a predetermined position in the image display region is notobtained, and it is difficult to perform correct image displaycorresponding to an inputted image signal.

To address such a disadvantage, for example, it is conceivable to employa method of making the opening of the shadow mask larger than theopening of the insulating layer, and forming an organic layer greatlyextending off the emission region to the insulating layer. This makes itpossible to fill each emission region with a predetermined organic layerreliably.

In this case however, ends of the organic layers of organiclight-emission elements adjacent to each other are in a condition ofoverlapping each other. Therefore, there is a possibility that a holeinjection layer in one organic layer overlaying the end of the otherorganic layer may touch a cathode electrode covering those organiclayers. In such a case, a conduction path is formed between an anodeelectrode and the cathode electrode via the hole injection layer, and aleakage current flows. Therefore, there is a possibility that control ofdriving each organic light-emission element may not be performedsufficiently, and normal image display in an organic EL display may bedisturbed. In particular, when a leakage current flows between organiclight-emission elements that emit light of different colors, this maycause a color mixture in the display image.

Therefore, the present applicant has already proposed a method ofproviding a separation film having a wall surface shaped like anoverhang to surround each light-emission element, and separating organiclayers as well as cathode electrodes in the adjacent light-emissionelements from each other (for example, see Japanese Unexamined PatentApplication Publication No. 2010-44894).

SUMMARY

However, it is expected that a further increase in the numericalaperture will be demanded in future. Therefore, there is desired adisplay device that may reliably prevent a leakage current fromoccurring even in such a case.

In view of the foregoing, it is desirable to provide a display devicesuitable for increase in a numerical aperture and allowed to exhibitbetter display performance, and a method of producing the displaydevice.

According to an embodiment of the present disclosure, there is provideda display device including: a substrate; a plurality of light-emissionelements arranged, on the substrate in a first direction and a seconddirection intersecting each other, each of the light-emission elementshaving a first electrode layer, an organic layer including a luminouslayer, and a second electrode layer which are laminated in that order;and a separation section disposed, on the substrate, between thelight-emission elements adjacent to each other in the first direction,the separation section having two or more pairs of steps. The firstelectrode layers in the light-emission elements are separated from eachother, and the organic layers as well as the second electrode layers inthe light-emission elements adjacent to each other in the firstdirection are separated from each other by the steps included in theseparation section. Here, it is preferable that, for example, thelight-emission elements emitting light of colors equal to each other bealigned in the second direction, and the light-emission elementsemitting light of different colors be aligned in the first direction.

According to another embodiment of the present disclosure, there isprovided a method of producing a display device having: a substrate; aplurality of light-emission elements arranged, on the substrate, in afirst direction and a second direction intersecting each other, each ofthe light-emission elements having a first electrode layer, an organiclayer including a luminous layer, and a second electrode layer which arelaminated in that order; and a separation section disposed, on thesubstrate, between the light-emission elements adjacent to each other inthe first direction, the separation section having two or more pairs ofsteps. The method includes the followings steps.

(A) Forming a plurality of first electrode layers on the substrate to bearranged away from each other.(B) Forming an insulating layer filling a gap between the plurality offirst electrode layers to form a separation section.(C) Forming two or more pairs of steps in the insulating layer of theseparation section.(D) Forming a plurality of organic layers including a luminous layersequentially to cover the entire of the first electrode layers and theinsulating layer of the separation section.(E) Forming a second electrode layer to cover the organic layers.

Here, at the time of forming the organic layer and the second electrodelayer, the organic layers as well as the second electrode layers in thelight-emission elements adjacent to each other in the first directionare separated from each other by the steps included in the separationsection.

In the display device and the method of producing the display deviceaccording to the above-described embodiments of the present disclosure,the second electrode layers as well as the organic layers in thelight-emission elements adjacent to each other in the first directionare separated from each other by the two or more pairs of steps includedin the separation section. Therefore, leakage of a driving currentbetween the light-emission elements adjacent to each other in the firstdirection is avoided. Here, in a case where the light-emission elementsadjacent to each other in the first direction are elements emittinglight of different colors, a color shift is prevented.

According to the display device and the method of producing the displaydevice in the above-described embodiments of the present disclosure, thesecond electrode layers as well as the organic layers in thelight-emission elements adjacent to each other in the first directionare separated from each other by the two or more pairs of steps includedin the separation section. Therefore, it is possible to reliably preventa short circuit between the first electrode layer and the secondelectrode layer and a short circuit between the first electrode layersadjacent to each other, even when an overlap between the organic layersoccurs due to narrowing of a distance between the light-emissionelements adjacent to each other in the first direction. For this reason,it is possible to perform control of driving each of the light-emissionelements sufficiently, while supporting the narrowing of the distancebetween the light-emission elements. As a result, it is possible toexhibit high display performance such as excellence in uniformity oflight-emission luminance distribution and color separability in an imagedisplay region, while securing a high numerical aperture.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of thetechnology.

FIG. 1 is a diagram illustrating a configuration of a display deviceaccording to an embodiment of the present disclosure.

FIG. 2 is a diagram illustrating an example of a pixel driving circuitillustrated in FIG. 1.

FIG. 3 is a plan view illustrating a configuration of a display regionillustrated in FIG. 1.

FIG. 4 is a cross-sectional diagram illustrating a configuration of thedisplay region illustrated in FIG. 1.

FIG. 5 is another cross-sectional diagram illustrating a configurationof the display region illustrated in FIG. 1.

FIG. 6 is an enlarged cross-sectional diagram illustrating aconfigurational example of a concave section in an element separatinginsulating layer illustrated in FIG. 4.

FIG. 7 is an enlarged cross-sectional diagram illustrating anotherconfigurational example of the concave section in the element separatinginsulating layer illustrated in FIG. 4.

FIG. 8 is a plan view illustrating a configuration of apixel-driving-circuit forming layer illustrated in FIG. 4.

FIG. 9 is an enlarged cross-sectional diagram illustrating an organiclayer illustrated in FIG. 4.

FIG. 10 is a schematic diagram illustrating a planar shape of a secondelectrode layer provided on a substrate of FIG. 1 and a wiring patterntherearound.

FIGS. 11A to 11D are cross-sectional diagrams illustrating one processin a method of producing the display device illustrated in FIG. 1.

FIG. 12 is a cross-sectional diagram illustrating a configuration of amain part of a display device serving as a first modification.

FIG. 13 is a cross-sectional diagram illustrating a configuration of amain part of a display device serving as a second modification.

FIG. 14 is a cross-sectional diagram illustrating a configuration of amain part of a display device serving as a third modification.

DETAILED DESCRIPTION OF EMBODIMENTS

An embodiment of the present disclosure (hereinafter merely referred toas the embodiment) will be described below in detail with reference tothe drawings.

FIG. 1 illustrates a configuration of a display device using an organiclight-emission element according to an embodiment in the presentdisclosure. This display device is used as an extra-thin organiclight-emitting color display device or the like. In this display device,a display region 110 is formed on a board 111. Around the display region110 on the board 111, a signal-line driving circuit 120 that is a driverfor image display, a scanning-line driving circuit 130, and apower-supply-line driving circuit 140 are formed, for example.

Formed in the display region 110 are a plurality of organiclight-emission elements 10 (10R, 10G, and 10B) two-dimensionallyarranged in the form of a matrix, and a pixel driving circuit 150 fordriving the organic light-emission elements. In the pixel drivingcircuit 150, a plurality of signal lines 120A (120A1, 120A2, . . . ,120Am, . . . ) are arranged in a column direction (Y-axis direction),and a plurality of scanning lines 130A (130A1, . . . , 130An, . . . )and a plurality of power supply lines 140A (140A1, . . . , 140An, . . .) are arranged in a row direction (X-axis direction). Any one of theorganic light-emission elements 10R, 10G, and 10B is associated with andprovided at an intersection between each of the signal lines 120A andeach of the scanning lines 130A. Each of the signal lines 120A isconnected to the signal-line driving circuit 120, each of the scanninglines 130A is connected to the scanning-line driving circuit 130, andeach of the power supply lines 140A is connected to thepower-supply-line driving circuit 140.

The signal-line driving circuit 120 supplies a signal voltage of animage signal supplied from a signal supply source (not illustrated) andcorresponding to luminous information, to the organic light-emissionelements 10R, 10G, and 10B selected via the signal line 120A.

The scanning-line driving circuit 130 is configured by using a shiftregister and the like, the shift register sequentially shifting(transferring) start pulses in synchronization with inputted clockpulses. The scanning-line driving circuit 130 scans each of the organiclight-emission elements 10R, 10G, and 10B on a line-by-line basis at thetime of writing an image signal to each of the organic light-emissionelements 10R, 10G, and 10B, and supplies a scanning signal to each ofthe scanning lines 130A sequentially.

The power-supply-line driving circuit 140 is configured by using a shiftregister and the like, the shift register sequentially shifting(transferring) start pulses in synchronization with inputted clockpulses. The power-supply-line driving circuit 140 appropriately supplieseither of a first electric potential and a second electric potentialdifferent from each other to each of the power supply lines 140A, insynchronization with the scanning on a line-by-line basis by thescanning-line driving circuit 130. This makes a selection of aconduction state or a non-conduction state of a drive transistor Tr1 tobe described later.

The pixel driving circuit 150 is provided in a tier (apixel-driving-circuit forming layer 112 to be described later) betweenthe board 111 and the organic light-emission element 10. Aconfigurational example of the pixel driving circuit 150 is illustratedin FIG. 2. As illustrated in FIG. 2, the pixel driving circuit 150 is anactive driving circuit having the drive transistor Tr1 as well as awrite transistor Tr2, a capacitor (retention capacitor) Cs providedbetween the transistors Tr1 and Tr2, and the organic light-emissionelement 10. The organic light-emission element 10 is connected to thedrive transistor Tr1 in series between the power supply line 140A and acommon power supply line (GND). Each of the drive transistor Tr1 and thewrite transistor Tr2 may be configured by using a general thin-filmtransistor (TFT), and its structure may be, for example, an invertedstaggered structure (a so-called bottom gate type) or a staggeredstructure (a top gate type), and is not limited in particular.

The write transistor Tr2 has a drain electrode connected to the signalline 120A, for example, and is supplied with the image signal from thesignal-line driving circuit 120. Further, the write transistor Tr2 has agate electrode connected to the scanning line 130A, and is supplied withthe scanning signal from the scanning-line driving circuit 130.Furthermore, the write transistor Tr2 has a source electrode connectedto a gate electrode of the drive transistor Tr1.

The drive transistor Tr1 has a drain electrode connected to the powersupply line 140A, for example, and the drain electrode is set to eitherthe first electric potential or the second electric potential by thepower-supply-line driving circuit 140. The drive transistor Tr1 has asource electrode connected to the organic light-emission element 10.

The retention capacitor Cs is formed between the gate electrode of thedrive transistor Tr1 (the source electrode of the write transistor Tr2)and the source electrode of the drive transistor Tr1.

FIG. 3 illustrates a configurational example of the display region 110spreading on an XY plane. Here, there is illustrated a planeconfiguration when the display region 110 in a state of a secondelectrode layer 16, a protective film 18, and a sealing substrate 19(each will be described later) being removed is viewed from above.

In the display region 110, the organic light-emission elements 10 aresequentially arranged in the form of a matrix as a whole. To be morespecific, an element separating insulating layer 24 is provided in theform of a lattice, and the organic light-emission elements 10R, 10G, and10B are each disposed at each region defined thereby. The organiclight-emission elements 10R, 10G, and 10B each include an emissionregion 20 with an outline defined by an opening 24K1 of the elementseparating insulating layer 24. The organic light-emission element 10Remits red light, the organic light-emission element 10G emits greenlight, and the organic light-emission element 10B emits blue light.Here, the organic light-emission elements 10 emitting light of the samecolor are arranged in one line in the Y-axis direction, and this oneline is repeated sequentially in the X-axis direction. Therefore, acombination of the organic light-emission elements 10R, 10G, and 10Badjacent in the X-axis direction forms a picture element (pixel).

In the element separating insulating layer 24, a metal layer 17 isembedded to surround each of the organic light-emission elements 10. Themetal layer 17 has parts extending in the X-axis direction and partsextending in the Y-axis direction, which are integral to be in the formof a lattice. In addition, in FIG. 3, a rectangular broken linesurrounding the emission region 20 indicates a first electrode layer 13(to be described later) included in the organic light-emission element10. In addition, the element separating insulating layer 24 is providedwith a plurality of openings 24K2 each formed in a region between theorganic light-emission elements 10 adjacent to each other in the Y-axisdirection and overlapping the metal layer 17. In the region surroundedby this opening 24K2, a connection section 21 (a part surrounded by abroken line) to make connection between the metal layer 17 and thesecond electrode layer 16 of the organic light-emission element 10 isprovided. It is to be noted that the number of the organiclight-emission elements 10 arranged in the X direction and the Ydirection is arbitrarily set, and is not limited to the numberillustrated in FIG. 3. Moreover, one pixel may be formed of four or moreorganic light-emission elements, or an organic light-emission elementthat emits white light may be further provided.

FIG. 4 illustrates a schematic structure of an XZ section of the displayregion 110, taken along a line IV-IV illustrated in FIG. 3. Further,FIG. 5 illustrates a schematic structure of a YZ section of the displayregion 110, taken along a line V-V illustrated in FIG. 3. As illustratedin FIG. 4 and FIG. 5, in the display region 110, on a substrate 11formed by providing the pixel-driving-circuit forming layer 112 on theboard 111, a light-emission element forming layer 12 including theorganic light-emission elements 10 is formed. On the organiclight-emission elements 10, the protective film 18 and the sealingsubstrate 19 are sequentially formed to cover the whole. Each of theorganic light-emission elements 10 is an element in which the firstelectrode layer 13 serving as an anode electrode, an organic layer 14including a luminous layer 14C (to be described later), the secondelectrode layer 16 serving as a cathode electrode are laminatedsequentially from the board 111 side. The organic layers 14 as well asthe first electrode layers 13 are separated for every organiclight-emission element 10 by the element separating insulating layer 24.Further, the second electrode layer 16 in each of the organiclight-emission elements 10 is separated from the second electrode layer16 in each of other organic light-emission elements 10 adjacent in theX-axis direction, due to existence of the insulating layer 24 located ina gap region VZ and serving as a separation section (see FIG. 4). It isto be noted that the gap region VZ is a region between the organiclight-emission elements 10 adjacent to each other in the X-axisdirection. On the other hand, the second electrode layers 16 in therespective organic light-emission elements 10 adjacent to each other inthe Y-axis direction are combined with each other (see FIG. 5). It is tobe noted that the metal layer 17 is embedded in the element separatinginsulating layer 24, except a region corresponding to the opening 24K2.

The element separating insulating layer 24 is provided to fill a gapbetween the first electrode layers 13 as well as the organic layers 14in the respective organic light-emission elements 10 adjacent to eachother. The element separating insulating layer 24 is made of an organicmaterial, e.g., polyimide, and ensures insulation between the firstelectrode layer 13 and the second electrode layer 16 as well as themetal layer 17, while precisely defining the emission region 20 of theorganic light-emission element 10.

In addition, the gap region VZ of the insulating layer 24 is providedwith a concave section 24G, and thereby two pairs of steps are formed.FIG. 6 illustrates an enlarged view of a part near the concave section24G illustrated in FIG. 4. The two pairs of steps here are; steps formedby a top surface 24TS1 and a bottom 24BS1, and steps formed by a topsurface 24TS2 and the bottom 24BS1. In addition, it is desirable that ina thickness direction (Z-axis direction), a difference between the topsurfaces 24TS1 and 24TS2 at the highest position of the elementseparating insulating layer 24, (the maximum height position in theelement separating insulating layer 24) and the position of a surface13S of the first electrode layer 13 be larger than the total thicknessof the organic layer 14 and the second electrode layer 16.

In the concave section 24G, one or both of angles α and β formed by thetop surfaces 24TS1 and 24TS2 and sidewalls WS1 and WS2 are 90 degrees orless (preferably, less than 90 degrees). Specifically, as illustrated inFIG. 6, for example, this is a part where portions on both sides of theconcave section 24G each have a rectangular shape in cross section, oras in another configurational example illustrated in FIG. 7, a partwhere portions on both sides of the concave section 24G each have areversed trapezoidal shape in cross section. Thanks to such a concavesection 24G, even when materials forming the organic layer 14 and thesecond electrode layer 16 are deposited on the entire display region 110at a time by, for example, vapor deposition, the organic layers 14 aswell as the second electrode layer 16 in the respective organiclight-emission elements 10 adjacent in the X-axis direction are reliablyseparated from each other. This is because the angles α and β at edgesEG1 and EG2 are 90 degrees or less and thus, deposed materials do noteasily accumulate in their neighborhood, resulting in a break between:the organic layer 14 as well as the second electrode layer 16 providedin the emission region 20; and an organic layer 14Z as well as a secondelectrode layer 16Z covering the top surfaces 24TS1 and 24TS2, and thebottom 24BS1, at each of the edges EG1 and EG2. In particular, when theportions on both sides of the concave section 24G each have the reversedtrapezoidal shape in cross section as in FIG. 7, the organic layers 14as well as the second electrode layers 16 are separated from each othermore reliably.

The protective film 18 covering the organic light-emission element 10 ismade of an insulating material such as silicon nitride (SiNx). Further,the sealing substrate 19 provided thereon seals the organiclight-emission element 10 together with the protective film 18 and anadhesive layer (not illustrated), and is made of a material such astransparent glass which allows light produced in the luminous layer 14Cto pass therethrough.

Next, with reference to FIG. 8 and FIG. 9 in addition to FIG. 4 to FIG.6, there will be described a detailed configuration of each of thesubstrate 11 and the organic light-emission element 10. It is to benoted that the organic light-emission elements 10R, 10G, and 10B arepartially different in terms of the configuration of the organic layer14, but otherwise have the same configuration, and thus will bedescribed collectively.

FIG. 8 is a schematic diagram illustrating a plane configuration of thepixel driving circuit 150 provided in the pixel-driving-circuit forminglayer 112, in one of the organic light-emission elements 10.

The substrate 11 is an element where the pixel-driving-circuit forminglayer 112 including the pixel driving circuit 150 is provided on theboard 111 made of glass, silicon (Si) wafer, resin, or the like. On thesurface of the board 111, a metal layer 211G that is the gate electrodeof the drive transistor Tr1, a metal layer 221G that is the gateelectrode of the write transistor Tr2, and a part of the signal line120A are provided as metal layers of a first tier. These metal layers211G and 221G and the signal line 120A are covered with a gateinsulating film (not illustrated) made of silicon nitride, siliconoxide, or the like.

In the drive transistor Tr1, a part of the region on the gate insulatingfilm, which part corresponds to the metal layer 211G, is provided with achannel layer (not illustrated) of a semiconductor thin film made ofamorphous silicon or the like. On the channel layer, an insulatingchannel protective film (not illustrated) is provided to occupy achannel region that is a central region thereof, and a drain electrode(not illustrated) and a source electrode (not illustrated) each formedof an n-type semiconductor thin film made of n-type amorphous silicon orthe like are provided in regions on both sides thereof. These drainelectrode and source electrode are separated from each other by thechannel protective film mentioned above, and their respective end facesare apart from each other across the channel region interposed inbetween. Further, a metal layer 216D serving as a drain wire and a metallayer 216S serving as a source wire are provided as metal layers of asecond tier, so as to cover the drain electrode and the sourceelectrode, respectively. The metal layer 216D and the metal layer 216Seach have a structure in which, for example, a titanium (Ti) layer, analuminum (Al) layer, and a titanium layer are laminated sequentially.The write transistor Tr2 has a configuration similar to that of thedrive transistor Tr1. It is to be noted that in FIG. 8, the metal layer221G serving as the metal layer of the first tier, a metal layer 226D(drain wire) and a metal layer 226S (source wire) serving as metallayers of the second tier are illustrated as components of the writetransistor Tr2.

As the metal layers of the second tier, other than the metal layers 216Dand 226D and the metal layers 2165 and 226S mentioned above, thescanning line 130A and the power supply line 140A are provided. It is tobe noted that, here, the drive transistor Tr1 and the write transistorTr2 in the inverted staggered structure (so-called bottom gate type)have been described, but they may be in the staggered structure(so-called top gate type). Further, the signal line 120A is provided asa metal layer of the second tier, in a region except the intersectionbetween the scanning line 130A and the power supply line 140A.

The pixel driving circuit 150 is covered as a whole by the protectivefilm (not illustrated) made of silicon nitride or the like and further,an insulating flattening film (not illustrated) is provided thereon. Itis desirable that the flattening film have a surface with extremely highsurface smoothness. In addition, in part of the flattening film and theprotective film, a minute connection hole 124 is provided (see FIG. 8).It is desirable that the flattening film be made of a material with highpattern precision such as an organic material of polyimide or the like.The connection hole 124 is filled with the first electrode layer 13,which establishes conduction with the metal layer 216S forming thesource wire of the drive transistor Tr1.

The first electrode layer 13 is formed on the flattening film that isthe uppermost layer of the pixel-driving-circuit forming layer 112, andalso functions as a reflective layer. For this reason, it is desirablethat the first electrode layer 13 be made of a material having a highestpossible reflectance, in order to increase luminous efficiency.Specifically, the first electrode layer 13 is made of a high reflectancematerial such as aluminum (Al) or aluminum neodymium alloy (AlNd). It isto be noted that aluminum has low resistance to a developer used in adevelopment process at the time of forming the openings 24K1 and 24K2 ofthe element separating insulating layer 24 and thus, easily corrodes. Incontrast, AlNd has high resistance to a developer and does not easilycorrode. Therefore, it is recommended that the first electrode layer 13be a single-layer structure made of AlNd, or a two-layer structureincluding an aluminum layer and AlNd (Al layer (lower layer)/AlNd layer(upper layer)). In particular, in the case of the two-layer structure ofthe Al layer (lower layer)/the AlNd layer (upper layer), the resistancebecomes low compared to the single-layer structure of the AlNd layer andthus, this case is desirable. The overall thickness of the firstelectrode layer 13 is, for example, 100 nm or more and 1,000 nm or less.Further, the first electrode layer 13 may have a two-layer structure, anupper layer thereof (a layer contacting the organic layer 14) may bemade of the high reflectance material mentioned above, and a lower layerthereof (a layer contacting the flattening film of thepixel-driving-circuit forming layer 112) may be made of a lowreflectance material such as molybdenum (Mo) or its compound (alloy).This is because thus providing the layer having a high light absorptionrate on the surface contacting the pixel-driving-circuit forming layer112 provided with the drive transistor Tr1 and the write transistor Tr2makes it possible to absorb external light or unwanted light such aslight leaking from the organic light-emission element 10. It is to benoted that the first electrode layer 13 is formed, as described above,to cover the surface of the flattening film, and fill the connectionhole 124.

The organic layer 14 is formed over the entire surface of the emissionregion 20 defined by the element separating insulating layer 24 with nogap. The organic layer 14 has, as illustrated in FIG. 9, for example, aconfiguration in which a hole injection layer 14A, a hole transportlayer 14B, the luminous layer 14C, and an electron transport layer 14Dare laminated sequentially from the first electrode layer 13 side.However, the layers except the luminous layer 14C may be providedoptionally. It is to be noted that FIG. 9 illustrates an enlarged partof a section of the organic layer 14 illustrated in FIG. 4 to FIG. 6.

The hole injection layer 14A is a buffer layer to increase holeinjection efficiency, and prevent leakage. The hole transport layer 14Bis intended to increase hole transport efficiency to the luminous layer14C. The luminous layer 14C produces light with the application of anelectric field, causing recombination between electron and positivehole. The electron transport layer 14D is intended to increase electrontransport efficiency to the luminous layer 14C. It is to be noted thatbetween the electron transport layer 14D and the second electrode layer16, an electronic injection layer (not illustrated) made of LiF, Li₂O,or the like may be provided.

Further, the organic layers 14 vary in configuration, depending on theluminous colors of the organic light-emission elements 10R, 10G, and10B. The hole injection layer 14A of the organic light-emission element10R has, for example, a thickness of 5 nm or more and 300 nm or less,and is made of 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine(m-MTDATA), or 4,4′,4″-tris(2-naphthylphenylamino)triphenylamine(2-TNATA). The hole transport layer 14B of the organic light-emissionelement 10R has, for example, a thickness of 5 nm or more and 300 nm orless, and is made of bis[(N-naphthyl)-N-phenyl]benzidine (a-NPD). Theluminous layer 14C of the organic light-emission element 10R has, forexample, a thickness of 10 nm or more and 100 nm or less, and is made of8-quinolinol aluminum complex (Alq₃) mixed with 40 vol % of2,6-bis[4-[N-(4-methoxyphenyl)-N-phenyl]aminostyryl]naphthalene-1,5-dicarbonitrile(BSN-BCN). The electron transport layer 14D of the organiclight-emission element 10R has, for example, a thickness of 5 nm or moreand 300 nm or less, and is made of Alq₃.

The hole injection layer 14A of the organic light-emission element 10Ghas, for example, a thickness of 5 nm or more and 300 nm or less, and ismade of m-MTDATA or 2-TNATA. The hole transport layer 14B of the organiclight-emission element 10G has, for example, a thickness of 5 nm or moreand 300 nm or less, and is made of a-NPD. The luminous layer 14C of theorganic light-emission element 10G has, for example, a thickness of 10nm or more and 300 nm or less, and is made of Alq₃ mixed with 3 vol % ofCoumarin 6. The electron transport layer 14D of the organiclight-emission element 10G has, for example, a thickness of 5 nm or moreand 300 nm or less, and is made of Alq₃.

The hole injection layer 14A of the organic light-emission element 10Bhas, for example, a thickness of 5 nm or more and 300 nm or less, and ismade of m-MTDATA or 2-TNATA. The hole transport layer 14B of the organiclight-emission element 10B has, for example, a thickness of 5 nm or moreand 300 nm or less, and is made of α-NPD. The luminous layer 14C of theorganic light-emission element 10B has, for example, a thickness of 10nm or more and 100 nm or less, and is made of spiro 6Φ. The electrontransport layer 14D of the organic light-emission element 10B has, forexample, a thickness of 5 nm or more and 300 nm or less, and is made ofAlq₃.

The second electrode layer 16 has, for example, a thickness of 5 nm ormore and 50 nm or less, and is made of a simple substance or an alloy ofa metallic element such as aluminum (Al), magnesium (Mg), calcium (Ca),or sodium (Na). Above all, an alloy of magnesium and silver (MgAgalloy), or an alloy of aluminum (Al) and lithium (Li) (AlLi alloy) ispreferable. The second electrode layer 16 is, for example, providedcommonly for all the organic light-emission elements 10R, 10G, and 10B,and disposed to face the first electrode layer 13 of each of the organiclight-emission elements 10R, 10G, and 10B. Further, the second electrodelayer 16 is formed to cover not only the organic layer 14 but theelement separating insulating layer 24 as well.

The second electrode layers 16 in the respective organic light-emissionelements 10 adjacent to each other are, as described above, separatedfrom each other by the element separating insulating layer 24 of the gapregion VZ in the X-axis direction, while connected in the Y-axisdirection. Therefore, its planar shape is a rectangle whose longitudinaldirection is the Y direction as illustrated in FIG. 10. FIG. 10 is aschematic diagram illustrating a planar shape of the second electrodelayer 16 provided on the board 111 and a wiring pattern therearound. Asillustrated in FIG. 10, in this display device, the second electrodelayers 16 each extend in the Y direction to pass through the displayregion 110, and are aligned in the X-axis direction. Further, both endsof each of the second electrode layers 16 are connected to a commonwiring pattern, and connected to the common power supply line GND (seeFIG. 2) via pads P1 and P2.

The metal layer 17 is formed on the surface of the pixel-driving-circuitforming layer 112 like the first electrode layer 13, and functions as anauxiliary wire compensating for a voltage drop in the second electrodelayer 16 serving as a main electrode. The metal layer 17 is in contactwith the second electrode layer 16 in the opening 24K2, and forms theconnection section 21 connected electrically to the second electrodelayer 16 (see FIG. 3 and FIG. 5).

In a case where this metal layer 17 is not present, the electricpotential of the second electrode layer 16 connected to the common powersupply line GND (see FIG. 2) is not constant among the organiclight-emission elements 10R, 10G, and 10B, due to a voltage dropaccording to a distance from a power source (not illustrated) to each ofthe organic light-emission elements 10R, 10G, and 10B, and therebyremarkable variations easily occur. Such variations in the electricpotential of the second electrode layer 16 cause luminance unevenness ofthe display region 110 and thus are not desirable. The metal layer 17functions to suppress a voltage drop from the power source to the secondelectrode layer 16 to a minimum, and prevent the occurrence of suchluminance unevenness, even when a screen is enlarged in the displayregion 110. It is to be noted that in Japanese Unexamined PatentApplication Publication No. 2010-44894 mentioned above, cathodes 34 c inthe respective organic light-emission elements emitting light of thesame color also are separated from each other. In contrast, in thepresent embodiment, the organic light-emission elements 10 emittinglight of the same color are connected and thus, a voltage drop does noteasily occur. For this reason, the present embodiment is more suitablefor an increase in the screen of the display region 110.

This display device may be produced as follows, for example.

First, on the board 111 made of the above-described material, the pixeldriving circuit 150 including the drive transistor Tr1 and the writetransistor Tr2 is formed. Specifically, at first, a metal film is formedon the board 111 by, for example, sputtering. Subsequently, the metalfilm is patterned by, for example, a photolithography method, dryetching, or wet etching, and therefore the metal layers 211G and 221Gand a part of the signal line 120A are formed on the board 111. Next,the entire surface is covered by a gate insulating film. Further, achannel layer, a channel protective film, a drain electrode as well as asource electrode, and the metal layers 216D and 226D as well as themetal layers 216S and 226S are formed on the gate insulating filmsequentially, to be in a predetermined shape. Here, a part of the signalline 120A, the scanning line 130A, and the power supply line 140A areeach formed as a second metal layer, when the metal layers 216D and 226Das well as the metal layers 216S and 226S are formed. At the time, aconnection section connecting the metal layer 221G and the scanning line130A, a connection section connecting the metal layer 226D and thesignal line 120A, a connection section connecting the metal layer 226Sand the metal layer 211G are formed beforehand. Subsequently, the wholeis covered with the protective film, which completes the pixel drivingcircuit 150. At the time, at a predetermined position in the protectivefilm on the metal layer 216S, an opening is formed by dry etching or thelike.

After the pixel driving circuit 150 is formed, for example, aphotosensitive resin having polyimide as a main component is applied tothe entire surface by spin coating or the like. Subsequently, thephotosensitive resin is subjected to a photolithography process, andthereby the flattening film having the connection hole 124 is formed.Specifically, the connection hole 124 communicating with an openingprovided in a protective film is formed by, for example, selectiveexposure and development using a mask having an opening at apredetermined position. Subsequently, the flattening film may be burnedoptionally. As a result, the pixel-driving-circuit forming layer 112 isobtained.

Further, the first electrode layer 13 made of the above-describedpredetermined material and the metal layer 17 are formed. Specifically,after a metal film made of the above-mentioned material is formed overthe entire surface by, for example, sputtering, a resist pattern (notillustrated) in a predetermined shape is formed on the laminated film byusing a predetermined mask. Furthermore, using the resist pattern as amask, selective etching of the metal film is performed. At the time, thefirst electrode layer 13 is formed to cover the surface of theflattening film and fill the connection hole 124. Moreover, the metallayer 17 is formed on the surface of the flattening film so as tosurround the first electrode layer 13 and not to overlap the signal line120A. It is desirable that the metal layer 17 be formed by using thesame type of material as that of the first electrode layer 13, togetherwith the first electrode layer 13 at a time.

Subsequently, a gap between the first electrode layers 13 adjacent toeach other is filled, and the element separating insulating layer 24 isformed to cover the metal layer 17. At the time, the openings 24K1 and24K2 are formed at predetermined positions, and the concave section 24Gextending in the Y direction is formed in the gap region VZ. The concavesection 24G is formed by, for example, performing multiple exposureprocessing. Specifically, first, as illustrated in FIG. 11A, aninsulating film 24Z to become the element separating insulating layer 24later is formed to cover the entire pixel-driving-circuit forming layer112 provided with the first electrode layer 13 and the metal layer 17.Subsequently, as illustrated in FIG. 11B, a region R20 corresponding tothe emission region 20 is exposed through use of a photomask M1. Here,of the insulating film 24Z, a part in the thickness direction isentirely exposed. Subsequently, as illustrated in FIG. 11C, a regionR24G that is a part of the gap region VZ is exposed by using a photomaskM2. At the time, only a part reaching a predetermined depth from the topsurface of the insulating film 24Z is exposed by, for example,controlling exposure time. After that, the element separating insulatinglayer 24 including the concave section 24G as illustrated in FIG. 11D isobtained by performing a development process using a predetermineddeveloper and thereby removing an exposed part. Alternatively, theconcave section 24G may be formed by exposure processing using ahalf-tone mask. In this case, there is used a half-tone photomaskprovided with a first exposure section corresponding to the emissionregion 20 and a second exposure section corresponding to the concavesection 24G. This makes it possible to transfer a first exposed patterncorresponding to the emission region 20 and a second exposed patterncorresponding to the concave section 24G to the insulating film thatlater becomes the element separating insulating layer, at one exposure.Here, the first exposure section allows exposure light to passtherethrough sufficiently, while the second exposure section functionsto control transmittance of the exposure light. Controlling thetransmittance in the second exposure section makes it possible tocontrol the depth of the concave section 24G. According to such exposureprocessing using the half-tone mask, it is possible to improveproductivity further.

Subsequently, the organic layer 14 is formed by sequentially laminatingthe hole injection layer 14A, the hole transport layer 14B, the luminouslayer 14C, and the electron transport layer 14D made of thepredetermined materials and having the predetermined thicknessesdescribed above by, for example, vapor deposition, to completely coverthe exposed part of the first electrode layer 13. Further, the secondelectrode layer 16 is formed to face the first electrode layer 13 tocover the organic layer 14 interposed therebetween and also cover theentire surface of the metal layer 17 in the connection section 21, andtherefore the organic light-emission element 10 is completed. At thetime, the organic layer 14 and the second electrode layer 16 are dividedin the X-axis direction by the edges EG1 and EG2 of the concave section24G.

Subsequently, the protective film 18 made of the material describedabove is formed to cover the whole. Finally, an adhesive layer is formedon the protective film 18, and the sealing substrate 19 is affixedacross this adhesive layer interposed therebetween. As a result, thedisplay device is completed.

In the display device obtained in this way, the scanning signal issupplied through the gate electrode (the metal layer 221G) of the writetransistor Tr2 from the scanning-line driving circuit 130 to each pixel,and the image signal from the signal-line driving circuit 120 isretained at the retention capacitor Cs via the write transistor Tr2. Onthe other hand, the power-supply-line driving circuit 140 supplies thefirst electric potential higher than the second electric potential toeach of the power supply lines 140A in synchronization with the scanningperformed on a line-by-line basis by the scanning-line driving circuit130. As a result, the conduction state of the drive transistor Tr1 isselected, and a driving current Id is injected into each of the organiclight-emission elements 10R, 10G, and 10B, and thereby recombinationbetween positive hole and electron occurs, causing emission of light.Multipath reflection of this light occurs between the first electrodelayer 13 and the second electrode layer 16, and this light is extractedafter passing through the second electrode layer 16, the protective film18, and the sealing substrate 19.

As described above, in the present embodiment, the organic layers 14adjacent to each other and the second electrode layers 16 adjacent toeach other in the X-axis direction are separated from each other by theconcave section 24G of the element separating insulating layer 24 in thegap region VZ. For this reason, it is possible to reliably preventoccurrence of a short circuit between the first electrode layer 13 andthe second electrode layer 16 and a short circuit between the firstelectrode layers 13 adjacent to each other, even when an overlap betweenthe organic layers 14 occurs as a result of narrowing a mutual distancebetween the organic light-emission elements 10 of different colors. Inother words, it is possible to control driving of each of the organiclight-emission elements 10 sufficiently, while supporting the narrowingof the mutual distance between the organic light-emission elements 10.As a result, it is possible to exhibit high display performance such asexcellence in uniformity of light-emission luminance distribution andcolor separability in the display region 110, while securing a highnumerical aperture.

In addition, in the present embodiment, the second electrode layers 16extending in the Y-axis direction and aligned in the X-axis directionare naturally formed by forming the concave section 24G in the elementseparating insulating layer 24 beforehand, and depositing thepredetermined material to cover the entire display region 110.Therefore, the second electrode layers 16 reliably separated from eachother may be readily arranged at appropriate positions, without usinghigh-precision patterning.

Up to this point, the present technology has been described by using theembodiment, but is not limited to the embodiment, and may be variouslymodified. For example, in the embodiment described above, one concavesection 24G is provided in the element separating insulating layer 24and therefore the two pairs of steps are formed, but the presenttechnology is not limited to this example. For instance, as in a firstmodification in FIG. 12, two concave sections 24G1 and 24G2 may beformed in the element separating insulating layer 24, and many pairs ofsteps may be formed. Further, as in a second modification in FIG. 13,one or more than one convex sections 24T (24T1 and 24T2) may be formedin an element separating insulating layer 24. Furthermore, as in a thirdmodification illustrated in FIG. 14, element separation in the X-axisdirection may be performed through formation of two or more pairs ofsteps by denting a flattening film, a protective film, and the like of apixel-driving-circuit forming layer 112, without forming an elementseparating insulating layer 24. It is to be noted that FIG. 14 is across-sectional diagram corresponding to FIG. 4 in the above-describedembodiment. In any of these cases, effects similar to those in theembodiment are obtained.

In addition, in the embodiment described above, the light-emissionelements emitting light of the same color are aligned in the firstdirection (Y-axis direction), and the light-emission elements emittinglight of different colors are aligned in the second direction (X-axisdirection), but are not limited to this example. Light-emission elementsemitting light of different colors may be aligned in both the first andsecond directions. Moreover, the first direction and the seconddirection are not limited to being intersecting each other at rightangles, but may intersect each other at an angle other than 90 degrees.

Further, the present technology is not limited to the above-describedmaterial of each layer and the lamination order, or film formationmethod in the embodiment described above. For example, the embodimenthas been described for the case where when the first electrode layer 13is the anode and the second electrode layer 16 is the cathode, but thefirst electrode layer 13 may be a cathode and the second electrode layer16 may be an anode. Furthermore, the embodiment has been described aboveby using the configurations of the organic light-emission elements 10R,10G, and 10B specifically, but the layers may not be all provided, orother layers may be further provided. For example, a hole-injectionthin-film layer made of chromium oxide (III) (Cr₂O₃), ITO (Indium TinOxide: an oxide mixed film of indium (In) and tin (Sn)), or the like maybe provided between the first electrode layer 13 and the organic layer14.

In addition, the embodiment has been described above for the case wherethe second electrode layer 16 is configured by using a semi-transmissivereflective layer, but the second electrode layer 16 may have a structurein which a semi-transmissive reflective layer and a transparentelectrode are laminated sequentially from the first electrode layer 13side. This transparent electrode is intended to lower the electricalresistance of the semi-transmissive reflective layer, and is made of aconductive material being sufficiently translucent with respect to lightproduced in a luminous layer. As a material forming the transparentelectrode, for example, a compound including ITO or indium, zinc (Zn),and oxygen is preferable. This is because use of this material makes itpossible to obtain high conductivity, even if the film is formed at roomtemperature. The thickness of the transparent electrode may be, forexample, 30 nm or more and 1,000 nm or less. In this case, there mayformed a resonator structure in which the semi-transmissive reflectivelayer is provided as one end, the other end is provided at a positionopposite to the semi-transmissive electrode across the transparentelectrode interposed in between, and the transparent electrode serves asa resonance section. Moreover, when such a resonator structure isprovided, the organic light-emission elements 10R, 10G, and 10B may becovered with the protective film 18, and this protective film 18 may bemade of a material having a refractive index in about the same level asthat of the material forming the transparent electrode, which makes itpossible to allow the protective film 18 to serve as a part of theresonance section and thus is desirable.

In addition, each of the embodiment and the like has been describedabove for the case of the active matrix display device, but the presenttechnology is also applicable to a passive matrix display device.Further, the configuration of the pixel driving circuit for activematrix driving is not limited to each of the embodiment and the likedescribed above, and a capacitive element or a transistor may be addedoptionally. In this case, according to a change in the pixel drivingcircuit, a desirable driving circuit may be added, other than thesignal-line driving circuit 120 and the scanning-line driving circuit130 described above.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2010-182470 filed in theJapan Patent Office on Aug. 17, 2010, the entire content of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A manufacturing method of a display device,comprising: providing a substrate; forming a plurality of firstelectrodes on the substrate, each of the first electrodes beingseparated from each other; forming a separation member between the firstelectrodes, the separation member having two or more pairs of steps;forming a plurality of organic elements respectively including anemission element, each of the plurality of organic elements respectivelycorresponding to one of the plurality of first electrodes, forming aplurality of second electrodes each respectively corresponding to one ofthe plurality of organic elements.
 2. The manufacturing method accordingto claim 1, wherein said forming the plurality of organic elementscomprises forming each of the plurality of organic elements at least inpart by separating an organic layer at the two or more pairs of thesteps.
 3. The manufacturing method according to claim 2, wherein saidforming the plurality of organic elements comprises covering theplurality of first electrodes and the separation member with the organiclayer.